According to the general prior art the structuring of foodstuffs can be accomplished in various ways. Two main routes can be distinguished:
(1) the structuring by biopolymers such as proteins and carbohydrates, and PA0 (2) the structuring by "particles" in the widest sense.
In the former case polymeric molecules cross-link to form a tangled, interconnected molecular network in water. In those systems the presence of junction zones or entanglements leads to gel formation and the enclosure of water. Examples of those polymeric substances are starch in puddings, gelatin in desserts and in the water phase of fat spreads, pectin in jams, carrageenin in desserts and in the water phase of fat spreads, and many others.
In the second case entities such as air cells, water droplets, fat droplets, crystals, starch granules or casein micelles are dispersed into the food system. Interaction forces between such particles determine the consistency and the physical stability of the food products. Many food systems fall into this category. In yoghurt aggregated protein particles form a network of protein strands. In mayonnaise an "interconnected" structure of oil droplets is responsible for its consistency. In a shortening fat crystals form an interconnected network structure enclosing oil. In a margarine water droplets are dispersed into a continuous network structure of fat crystals and oil. So, this represents a dispersion of particles in a network of particles. Even more complicated structures are found in butter and ice cream. But in all those cases a build-up of structure from particles of particle networks can be distinguished, which is responsible for the consistency of the finished products.
Heertje et al. WO 92/09209 published Jun. 11, 1992 discloses finished foodstuffs containing mesomorphic phase of edible surfactants as a structuring agent or fat replacer. The formation of mesomorphic phases of edible surfactant molecules and water can give rise to a firm texture and consistency. The use of this property of mesomorphic phases, to give consistency to products, is new to the food business. However, it should be noted that this use may already be known in other areas such as cosmetics and pharmaceuticals.
This new way of product structuring may be described e.g. as a regular, molecular arrangement of surfactant molecules with intervening aqueous regions. For the purpose of the invention the term mesomorphic phase is intended to include all semi-ordered phases of water and edible surfactant materials. Examples of mesomorphic phases are cubic, hexagonal, alpha crystalline gel, beta-crystalline coagel and lamellar phases. Preferred mesomorphic phases for use in accordance with the invention are lyotropic phases; also preferred are lamellar phases. For the purpose of the present invention, the term lamellar phase refers to any system having a pattern of alternating bilayers of edible surfactants and water. Examples of lamellar phases are lamellar droplet phases, lamellar gel phases and lamellar phases containing extended parallel layers of surfactants and water.
In the lamellar phase surfactants, are believed to form a bilayer structure. It is believed that a bulk lamellar phase consists of stacks of bi-layer structures with an intervening aqueous phase. Products according to the present invention preferably comprise bulk regions of the lamellar phase whereas it has been suggested that known products of the prior art might contain boundary layers of this phase at interfaces, such as those found around oil-droplets in water-continuous fatty products.
The bulk lamellar phase may be formed by temperature cycling of a mixture of surfactant and water. In the crystalline state, the surfactant molecules are oriented with adjacent hydrophillic groups and the hydrophobic chains are parallel and densely packed. On contact with water and heating to the so-called `Krafft` temperature it is believed that water penetrates between the adjacent `head` groups to form a `liquid crystal` structure. On cooling below the `Krafft` temperature, the hydrophobic chains pack into a regular lattice, producing a one-dimensionally periodic `sandwich` structure of alternating surfactant and aqueous layers.
As an example of the `gel` structure obtained: for a mixture of water and a distilled monoglyceride made from fully hydrogenated lard, which has been cycled above the Krafft temperature, X-ray diffraction in the low-angle region reveals that the thickness of the monoglyceride layers is of the order of 50-60 Angstrom. As the proportion of water in the mixture in the system is increased the inter-planar spacing increases, as water is taken up between the monoglyceride layers. It will be realised that the fine structure of the mesomorphic phase, especially as regards the inter-planar spacing, will vary when different surfactants are used.
Another preferred mesomorphic phase according to the invention is a beta-crystalline coagel, which is believed to consist of small plate-like crystals having an average thickness of less than 1 fm or even less than 0.1 fm, said platelets being dispersed in an aqueous environment. This is a suspension of beta-crystalline emulsifier in water and is also known as a `hydrate`. These coagels may be formed instead of an alpha crystalline gel phase under certain conditions, such as at acid pH. Both the above mentioned alpha gels and these hydrates are used extensively in the baking industry as crumb softening agents in wheat bread and as cake volume improvers, but it is believed that the structure of the mesomorphic phase is lost during product preparation and consequently that the finished foodstuff (be it bread or cake) does not contain bulk mesomorphic phase. In the context of the invention the coagel phase is considered a semi-ordered phase of water and edible surfactant (mesomorphic phase).
The presence of mesomorphic phases in food products may be detected by any method suitable for the detection of regular arrangements of surfactant materials. Suitable methods include for example NMR, Electron microscopy, Differential scanning calorimetry, light microscopy and X-ray diffraction.
Although reduction of fat while retaining suitable and customary organoleptic properties is a challenge in most foods, sandwich cookie filling creams have presented special difficulties. Fat reduction in sandwich cookie filling creams is complicated and has been only marginally successful. There is a need, therefore, for a sandwich cookie filling cream which posesses a reduced fat content yet enjoys similar organoleptic properties to its traditional full fat counterpart.
Consequently, the present invention relates in the first place to the use of mesomorphic phases of edible surfactants as structuring agent in cookie filling creams. This structuring leads to many useful properties, such as the use as fat replacer, lubricating agent, moisture retention agent and/or flavour release agent in the foodstuff. The invention also involves addition of mesomorphic phase of edible surfactants to other ingredients to replace fats in the filling cream.
With respect to the use as fat replacer it should be noted that the present invention can provide sandwich cookie filling creams which have reduced calorific contents as compared to the 28 to 35 wt. % fat found in normal filler creams. The present invention allows for the possibility of preparing cookie filling creams with fat-like properties, but with the use according to the present invention of 25% or less by weight of triglyceride fat, especially 20% or less by weight triglyceride fat, particularly from 5 to 18% by weight, and especially 5-10 wt. % triglyceride fat. Cookie filling creams which are triglyceride-fat free are also contemplated.
The present filling creams enjoy an improved shelf life and better sensory characteristics. Post hardening of the filling is less likely with the present compositions.
The triglyceride fat used herein is preferably in the form of an emulsified semi-solid or fluid. A suitable fat is a blend of Durkex 100 fluid high stability oil and Code 321. The Code 321 product has an SFI value @50.degree. F. of 34-43, @70.degree. F. of 12-22, @80.degree. F. of 16-19, @92.degree. F. of 3-8 and at 104 a maximum of 2. Durkex 100 and Code 321 oils are available from Van den Bergh Foods Company, Lisle, Ill. The fat blend may include emulsifiers and combinations thereof such as phosphated monoglycerides and lecithin. The phosphated monoglycerides and lecithin function as viscosity reducers. The phosphated monoglycerides can be used at from 1.5-2.5 wt. % and the lecithin can be used at from 0.5-1.2 wt %. Other emulsifiers such as polyglycerol esters, e.g., polyglycerol esters of oleic, ricinoleic and stearic acids, may be used to reduce the viscosity at levels of up to 4%, especially from 0.5 to 4%. Mono- and diglycerides may also be employed.
The triglyceride fat may be derived from any suitable source. Typically the fat will be a partially hydrogenated vegatable oil such as partially hydrogenated soybean or cottonseed ois. Other possible fat sources include palm oil, palm kernal oil, coconut oil, sunflower oil, or corn oil. An example of SFI values for a suitable fat blend would be @50.degree. F. 13-16.5, @70.degree. F. 8.4-9.5, @80.degree. F. 6.1-7.2 and at 104.degree. F. maximum 1.
The present invention permits a reduction in triglyceride fat content without requiring the high levels of glycerine (e.g., 14-18 wt. %) which are typical of prior reduced fat cookie creams. Reduction of glycerine is desirable in that it is a harsh tasting and costly ingredient. Levels of less than 13 wt. %, especially from 1 to 10%, and particularly from 5 to 8%, are contemplated herein. The invention permits addition of added moisture to the product for textural softening without adversely affecting product stability, e.g., shelf life. This allows for major reductions in the glycerine content. Typically, the additional moisture present in the product will be 0.5 to 10 wt. %, especially from 5 to 8 wt. % based on the total formula. Typical moisture levels in reduced fat sandwich cookie fillings are from 1 to 3%.
A particularly advantageous aspect of the invention pertains to a composition including the mesomorphic phase which can be used in the preparation of cookie filler creams. The composition includes a surfactant in the mesomorphic phase, a humectant such as polydextrose and optionally a preservative such as potassium sorbate. While not wishing to be bound by theory, it is believed that the humectant helps to stabilize the mesomorphic phase by binding water which becomes available. Other humectants might be employed, such as sorbitol, mannitol, xylitol, polyhydric alcohols (other than glycerine which is separately dealt with) and corn syrup solids. Generally a humectant which is not sucrose, dextrose, glucose, fructose or lactose is used. Humectants other than glycerine and sugars may be used at from 5-50 wt. % in the composition and from 1% and above in the cookie filling.
Non-fat dry milk, buttermilk solids, whole milk solids or soy protein may be added to contribute bulk to the preparation. Starches such as corn syrup solids and low DE maltodextrins may be used to increase plastic and yield values at high temperatures.
The cookie filler cream of the invention comprises mesomorphic phase of surfactant, glycerine, triglyceride fat, preservative and polydextrose. The filling creams may include polyglycerol esters.
The preferred ranges of for the mesomorphic phase in the filler cream is 1-15 wt. %.
Preferably food products in accordance with the invention contain at least 5% by volume of mesomorphic phase of edible surfactant, more preferred 10-100% by volume, for example 20-80% by volume, whereby the volume of the mesomorphic phase refers to the volume of the combined water/edible surfactant system.
The mesomorphic phase and its method of preparation is known to food scientists. In the "Lipid Handbook" of Gunstone, Harwood and Padley (Chapman and Hall, 1986) such phases are mentioned at page 227. Further detail may be found in "Food emulsions" of S. Friberg (Marcel Decker, 1976 at page 82).
Such mesomorphic phases may advantageously be formed by heating a mixture containing the edible surfactant and water to a temperature above the Krafft temperature, followed by cooling.
It should be noted further that the above mentioned Lipid Handbook mentions at page 227 the use of mesomorphic phases of saturated, distilled monoglycerides as additives for processed potatoes or cake emulsions. However, this application is used for aerating bakery batters and enhanced complexing with amylose in non-finished starch based products. In the former application the aerating effect is ascribed to the better distribution of the monoglycerides in the batter system and in the latter application the monoglycerides form insoluble complexes with amylose, responsible for the crumb softening effect in bread and the texture improving effects on potato products and pasta foods. The emulsifiers are added to the bakery products before baking and to the potato products before final processing and consequently there is no mesomorphic phase in the finished products. This would be unacceptable in those aspects of the present invention wherein presence of the mesomorphic phase in the final product is required.
In a preferred embodiment of the invention the mesomorphic phase is a lamellar gel phase. These phases are particularly preferred, because they can include a sensational amount of water, e.g. 98 or even 99 wt. %, based on the mesomorphic phase of edible surfactant and water.
Another preferred element of the present invention is the presence of bulk regions of mesomorphic phases in cookie filler creams. Most preferred is the presence of bulk regions of mesomorphic lamellar phases. Bulk phases preferably consist of either a more or less continuous mesomorphic phase or of discrete particles of mesomorphic phase, for example having a number average particle size of between 1 fm and 1,000 fm. In this respect it should be noted that it has been suggested that known products of the prior art might contain non-bulk boundary layers of the lamellar phase at o/w interfaces, such as those found around oil droplets in water-continuous fatty products. The bulk regions of mesomorphic phase of edible surfactants may advantageously be used for replacing the aqueous phase and/or oil phase in food products in accordance to the invention.
Cookie filler creams in accordance to the invention contain at least 1% by weight of mesomorphic phase of edible surfactant, more preferred at least 5% and preferably at least 10% by weight, for example 10-80% by weight wherein the weight of the mesomorphic phase refers to the weight of the combined water/edible surfactant system.
The filling creams of the invention can be prepared using conventional equipment such as a Hobart mixer. One preferred order for ingredient addition is first uniformly distributing any formula glycerine throughout the dry ingredients, then adding the mesophasic emulsion and mixing the warm or melted fat blend in thorougly. The filling can be warmed directly or by frictional heat to 95-105.degree. F. Any desired aeration can be accomplished by simultaneous high speed mixing and cooling to approximately 70.degree. F. Depositing of the filling onto base cookies can be accomplished with typical depositor equipment.
Biopolymers (other than those elsewhere mentioned herein) may advantageously be used in the present compositions to produce products which are less grainy and/or have a reduced tendency to lose moisture. The biopolymers may be added directly to the mesomorphic phase or otherwise incorporated directly in the mesomorphic phase. The biopolymer(s) may be present at a level of from, say, 0.05 to 30 wt. %, preferably between 0.1 and 25 wt. %. Suitable biopolymer materials are for example carbohydrates (for example modified starches or gums) and certain proteins. Examples of very suitable biopolymer materials are gelatin, soy protein, xanthan gum, carrageen, pectin, locust bean gum, modified starches (for example Paselli SA2 and N-oil) and microcrystalline cellulose and/or mixtures thereof with milk protein. Modified starch is preferably used at from 5-20%, gums preferably at 0.05 to 5% and gelatin at from 0.5 to 10 wt. %.
Also suitable may be the use of two or more different biopolymer materials. These materials are for example, used in a weight ratio of 1:10 to 10:1. An example of a suitable mixture of biopolymer materials is a combination of xanthan gum and locust bean gum. The use of biopolymers in spreads and dressings comprising mesomorphic phases of surfactants is described in the U.S. patent application of Heertje et al. Ser. No. 07/974,643, the disclosure of which is hereby incorporated by reference.
A further aspect of the invention relates to the finding that mesomorphic phases having relatively high levels of nonionic surfactant, e.g., 7wt % or higher, which tend to be quite brittle can be processed to yield a phase having a non-brittle texture by treatment after cooling in a colloid mill or by otherwise subjecting the phase to high shear without simultaneously cooling. Such processing is particularly useful in producing mesomorphic phases for the filler creams and ready-to-spread frosting or icings of the invention, but is also useful in finished foodstuffs generally. Finished foodstuffs including mesomorphic phases are described in the U.S. patent application of Heertje et al. Ser. No. 07/846,311, the disclosure of which is incorporated by reference herein. The invention comprises the process of treating the mesomorphic phases in the colloid mill (or otherwise subjecting the phase to high shear without contemporaneous cooling) after cooling and the finished foodstuffs incorporating such phases.
Another aspect of the present invention is the use of mesomorphic phases having high levels of nonionic surfactants, particularly saturated nonionic surfactants such as saturated monoglycerides. It has been found that mesomorphic phases having levels of nonionic surfactant of greater than 8 wt. % (based on the weight of the mesomorphic phase), e.g., from 8-15, especially 9-12% enjoy firmer texture. Such mesomorphic phases are particularly useful in filler creams and icings such as ready-to-spread frosting but are also useful in finished foodstuffs generally. Finished foodstuffs including mesomorphic phases are described in the U.S. patent application of Heertje et al. Ser. No. 07/846,311, the disclosure of which is incorporated by reference herein.